Hella Twin-Tone CompressorAir Horn Kit Installationby C. Jensen

(Click most graphics for a much larger view)

Click for one long blastfrom the Hellas

Click for two short blastsfrom the Hellas (coming soon)

Background

Ever since I saw the movie Cannonball Run back when I was young, I've always loved the
great sound of the European car horns. When that Lamborghini Countach pulled up (with the two
gorgeous women driving) and added the "1" in front of the 55 mph speed limit sign, they honked
their horn as they took off. They also honked when passing the cops as they toyed with the woefully
inadequate cop cars :-). So, ever since then I've been trying to find something similar for my Supra... then
I met Larry :-)

We (me and the rest of the PacNW chapter) met Larry (alias "The Cool Larry") Anderson during the
'97 SOGI Vegas meet. In a quirk of fate, Larry just happened to honk his horn and oh my God
he had the horns! We all couldn't believe it. He sounded exactly like an Italian sports
car. No more electric twangy "beep-beep" horns, but a true compressor powered pair of air
horns. I was hooked.

I took it upon myself to find those horns if it was the last thing I did :-)...

Well, after literally months of searching based on a part number that Larry got from some old
instructions he found, I finally did find those horns and I decided to put it all down in writing
so that the knowledge wasn't lost to history.

Part Information

The part number Larry gave me, 3PB-003-001, I found out (after much heartache) was the German
part number (read: jeez!). Finally, a store in Pennsylvania broke the code. Here is the information
necessary to order this part:

Part No. (German)

Part No. (US)

Description

3PB-003-001-791

85105

Hella Twin-Tone Compressor Horn

And here are the pictures of the correct packaging should you see it in the store:

Hella Horn Kit (Front)

Hella Horn Kit (Back)

Installation

Installation of the kit can be a little tricky depending on the model year Supra it's installed
into. Especially the final location of the compressor. There are very small, but nonetheless
important, details which can make or break a perfect install here. For example, the '91 and '92
Supras had a change to the power steering cooler rack which can get in the way of my location
for the compressor. I was not able to mount my compressor in the same location as Larry did on
his '87. Thus, some small customizing should be expected with this modification.

After a lot of trial-and-error and playing with the compressor I was finally able to mount it
using a Radio Shack universal bracket kit bracket on the passenger side hood bump stop bolt. Note
that the bracket holes had to be Dremel'd slightly larger to accept the larger diameter bolt.
The horns can be mounted, using the supplied brackets, in the stock mounting locations. Again,
though, Dremel'ing was necessary in order to widen the holes on one side in order to use the stock
bolts:

One thing I kept in mind while doing this was that I was planning on installing an HKS Intercooler
in the near future. Thus, I tried to keep everything out of the way of any of the new hardware
which would be going in. Specifically, I made sure that the horns were mounted behind the bumper's
center support brace since I knew that the HKS I/C didn't break that plane once installed. It took
a little more effort and tinkering, but I did it. You can see the final installation below:

Electrically, these horns couldn't be easier to install. The kit comes with a relay which is
designed to power the compressor via a direct power feed off the battery and is triggered by a
signal from the stock horn switch. Through experience from Larry it's been deemed unnecessary
for horn installations on Supras. The stock Supra relay and circuit is more than adequate to
power the Hella compressor. So, simply snip one of the stock plugs (I chose the one at the very
end) and splice in a wire with a standard female spade connector on one end (long enough to reach
to your desired compressor mount location). The grounding can be handled one of two ways. First,
via the bolt the compressor is hung by. This bolt is in direct contact with the compressor chassis
and is thus chassis grounded. I chose to avoid this since it's a rather sloppy way
(electrically speaking) to ground anything and grounded the compressor via the ground spade connector
and a tongue connector attached to one of the pop-up headlamp mounting bolts as seen below:

Everything was fully insulated using silicone tape which cures and provides a watertight bond
much more secure than electrical tape. I wrapped the air hoses with standard electrical harness
wrap to protect it and make it blend in much more naturally with the stock electronics. You can
see that below:

All-in-all I'm very happy with the quality of these horns so far and the quality of the sound is
outstanding. I'd guess that they're at least 30% louder than the stock horns and the tone will
definately get someone's attention :-) That's one dream down with a whole bunch still to go! :-)

(To get an idea of the sound of these horns, simply click the sound icons at the top of this page
or on the mods page)